Clinical characteristics of Korean type 2 diabetic patients in 2005

Korean type 2 diabetics differ from Western diabetics in showing non-obese but centrally obese anthropometry and relatively more insulin secretory defects than insulin resistance. We assessed insulin secretion based on fasting serum C-peptide level and insulin resistance using the short insulin tolerance test (Kitt; rate constant for plasma glucose disappearance) in 1601 type 2 diabetic Korean patients (831 men and 770 women). Insulin secretory defects were catergorized as severe (C-peptide < 1.10 ng/ml), moderate (C-peptide 1.10–1.69 ng/ml), and mild to non-secretory defect (C-peptide ≥ 1.70 ng/ml). Groups with a Kitt value of less than 2.5 %/min were considered insulin-resistant, while those with a Kitt value ≥2.5 %/min were considered insulin-sensitive. Overall, 42.5% of patients had a BMI ≥ 25.0 kg/m2, and 70.2% had a BMI ≥ 23.0 kg/m2; 45.2% (41.7% of men and 58.3% of women) were abdominally obese (waist ≥ 90 cm in men and 80 cm in women); mean fasting serum C-peptide level was 1.93 ± 0.90 ng/ml, and the mean Kitt value was 2.03 ± 0.96 %/min. Accordingly, 13, 33, and 54% of patients showed a severe, moderate, and mild to non-secretory defect, respectively; 70.6% were insulin-resistant; and 29.4% were insulin-sensitive. Obese type 2 diabetes is recently increasing in Korea, indicating a shift from insulin secretory defects to insulin resistance.